package com.headwind.util;

import java.sql.*;

/**
 * @author : Headwind
 * @version : 1.0
 * @date : Created in 2020/8/17
 * @description : 原始JDBC流程
 */
public class JdbcUtil {
    public static void main(String[] args) {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        try {
            //1、加载数据库驱动
            Class.forName("com.mysql.jdbc.Driver");
            //2、通过驱动管理类获取数据库链接
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/bicheng", "root", "root");
            //3、定义sql语句 ?表示占位符
            String sql = "select * from hw_mood where user_id = ?";
            //4、获取预处理statement
            preparedStatement = connection.prepareStatement(sql);
            //5、设置参数，第一个参数为sql语句中参数的序号（从1开始），第二个参数为设置的参数值
            preparedStatement.setString(1, "王五");
            //6、向数据库发出sql执行查询，查询出结果集
            resultSet = preparedStatement.executeQuery();
            //7、遍历查询结果集
            while (resultSet.next()) {
                System.out.println(resultSet.getString("id") + "  " + resultSet.getString("userId"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //8、释放资源
            if (resultSet != null) {
                try {
                    // 释放结果集
                    resultSet.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if (preparedStatement != null) {
                try {
                    // 关闭Statement
                    preparedStatement.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if (connection != null) {
                try {
                    // 关闭数据库连接
                    connection.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}
